This invention concerns a modular drainage unit intended for soil draining in general and draining around buildings and housing in particular.
The laying of a traditional drainage system is difficult and requires considerable and expensive means. In particular, it comprises the following operations: the digging of a trench, which is then lined with a geotextile fabric; a long pierced pipe (usually made from PVC) is then laid in the trench and covered with gravel; the geotextile fabric is folded over and the trench is filled in. Such a system therefore has many drawbacks. The geotextile fabric tends to slip down the sides of the trench when the gravel is poured and is frequently buried under the gravel. The drainage pipe tends to rise in the trench as a result of its rigidity and the vibration generated by pouring the gravel. When temperatures fall below xe2x88x9210xc2x0 C., the PVC pipe becomes brittle. Moreover, such drainage pipes are difficult to handle and therefore difficult to lay alone. The cost of laying is high, if one counts the purchase and delivery of the gravel and the labor required.
A number of solutions have been devised to solve part of these problems. Publication DE-A-22 07 216 describes a monoblock drainage unit with a square cross-section, traversed by a central longitudinal collecting conduit, made from a grainy material. This restricts the passage of the drainage water considerably and therefore does not permit effective drainage. Moreover, there is no system to direct the drainage water to the collecting conduit, and as a result part of the water is evacuated into the fill. Publication U.S. Pat No. 3,440,823 describes a drainage system with two separate components: a drainage conduit in the shape of an inverted V, placed on a impermeable base. The pipe comprises only very few side channels on the edges of the V, which are not sufficient to capture the drainage water. Moreover, the inverted-V shape is not resistant enough to crushing by the fill. Finally, publication NL-A-7 211 660 describes a drainage unit traversed by a central longitudinal collecting conduit. This unit is limited to the capture of rainwater in gutters, as it comprises openings only on its upper part.
Therefore, no existing system provides an effective, reliable, simple and economical solution to the problem of drainage.
The purpose of this invention is to supply such a solution, in the form of a drainage unit which is effective, practical, easy to use and able to capture and evacuate drainage water efficiently.
The invention comprises a modular drainage unit, characterized in that it comprises an elongated body, traversed by a longitudinal collecting conduit and comprising flow passages opening on the peripheral walls of said body and emerging into said collecting conduit, said flow passages being arranged to enable drainage water to circulate by gravity towards said collecting conduit, in that it comprises connecting means designed to assemble two consecutive drainage units and in that it comprises a water permeable outer casing.
The flow passages may take the form of peripheral grooves emerging into said collecting conduit by transverse channels, transverse channels running from said peripheral walls to said collecting conduit, peripheral baffles emerging into said collecting conduit by side channels, or the interstices of a porous structure forming said body.
In a preferred form of the invention, the connecting means comprise a coupling separate from said body, the outer dimensions of which do not exceed the bore of said collecting conduit, this coupling being designed to fit into the extremities facing the collecting conduits of two consecutive drainage units.
One possible variation is that the connecting means may comprise a coupling integral to said body, prolonging one of the extremities of the collecting conduit and designed to form a male part, the other extremity of the collecting conduit being designed to form a female part designed to receive the male part of an adjacent drainage unit.
The connecting means also advantageously comprise at least one lateral opening in said body at the same level as said collecting conduit, the dimensions of this lateral opening being more or less equal to those of said collecting conduit, emerging into the latter, and designed to receive said coupling designed to assemble two consecutive drainage units at right angles.
Depending on the preferred form of implementation, the outer casing is composed of a geotextile fabric, this fabric being wrapped around said body and being longer on one side, so as to cover partially the next drainage unit.
The body may be manufactured from a water impermeable material selected from the group comprising at least polystyrene, polyvinyl chloride, concrete, synthetic resin and any molded or extruded synthetic material.
The body may also be manufactured from a water permeable material selected from the group comprising at least expanded polystyrene and any structured or foamed synthetic material. In this case, the body may comprise a watertight area located under the collecting conduit and comprising a base made from an impermeable material incorporated in or under said body. The collecting conduit may also comprise a watertight inner casing, if necessary.